Surgical cutting instrument with electromechanical cutting

Abstract

A mechanical cutting device that makes use of mechanical (rotary) motion and suction to engage tissue also applies a cutting energy sufficient to vaporize the tissue. The rotation and suction are used to engage the tissue (sucking tissue into cutting windows when the cutting windows of inner and outer blades are aligned), and then the cutting member(s) function as an electrode(s) by having an electrical cutting signal applied thereto so that the cutting member(s) electrically cut the tissue as the cutting members relatively rotate. The electrical cutting signal is only applied as the windows become aligned up until the cutting of the tissue is completed. The cutting signal preferably is stopped after the cutting windows become misaligned. While the cutting windows are misaligned, a coagulation signal can be supplied to the cutting member so that the device functions as an electrocautery device.

What is claimed is: 
     
       1. A surgical cutting instrument comprising:
 a first cutting blade having a tubular body with a distal end and a proximal end, a cutting window that is sideward-facing disposed at the distal end and including a cutting edge; 
 a second cutting blade movably disposed inside the first cutting blade and having a distal cutting portion that, together with the cutting edge of the cutting window, cuts tissue by moving within the first cutting blade; 
 at least one first electrode located adjacent to at least the cutting edge at the distal end of the first cutting blade; and 
 control circuitry configured to control an electrical power signal supplied to the at least one first electrode, the control circuitry varying the electrical power signal based on a position of the second cutting blade relative to the first cutting blade, a rotating speed of the second cutting blade, or both. 
 
     
     
       2. The surgical cutting instrument of  claim 1 , wherein:
 the second cutting blade moves between a first position at which the tissue to be cut is permitted to enter the cutting window, and a second position at which the tissue has been cut by the cutting window, and 
 the control circuitry supplies (i) a first electrical power signal at least part of the time while the second cutting blade is in the first position, and (ii) a second electrical power signal, which is different from the first electrical power signal, at least part of the time while the second cutting blade is in the second position. 
 
     
     
       3. The surgical cutting instrument of  claim 2 , wherein the first electrical power signal causes the tissue to be cut. 
     
     
       4. The surgical cutting instrument of  claim 3 , wherein the second electrical power signal causes the tissue to be coagulated. 
     
     
       5. The surgical cutting instrument of  claim 3 , wherein the second electrical power signal is a zero power signal. 
     
     
       6. The surgical cutting instrument of  claim 2 , wherein the second electrical power signal causes the tissue to be coagulated. 
     
     
       7. The surgical cutting instrument of  claim 6 , wherein the first electrical power signal is a zero power signal. 
     
     
       8. The surgical cutting instrument of  claim 1 , wherein the electrical power signal supplied by the control circuitry is a monopolar signal. 
     
     
       9. The surgical cutting instrument of  claim 1 , further comprising:
 an insulation layer disposed over at least a portion of the distal end of the first cutting blade; and 
 at least one second electrode located over at least a portion of the insulation layer and electrically coupled to the control circuitry, 
 wherein the electrical power signal supplied by the control circuitry is a bipolar signal. 
 
     
     
       10. The surgical cutting instrument of  claim 1 , wherein suction is applied through the cutting window at the distal end of the first cutting blade. 
     
     
       11. The surgical cutting instrument of  claim 1 , wherein the second cutting blade rotates about a longitudinal axis of the surgical cutting instrument. 
     
     
       12. The surgical cutting instrument of  claim 1 , wherein the second cutting blade reciprocates in a longitudinal direction of the surgical cutting instrument. 
     
     
       13. The surgical cutting instrument of  claim 1 , wherein the control circuitry includes:
 a sensor that senses a position of the second cutting blade relative to the first cutting blade, a rotational speed of the second cutting blade, or both, and 
 a processor that varies the electrical power signal based on the sensed position of the second cutting blade relative to the first cutting blade. 
 
     
     
       14. The surgical cutting instrument of  claim 1 , wherein the control circuitry includes:
 at least one moving electrical contact coupled to the second cutting blade, and 
 at least one fixed contact that intermittently contacts the at least one moving electrical contact as the second cutting blade moves. 
 
     
     
       15. The surgical cutting instrument of  claim 1 , wherein:
 the second cutting blade moves between a first position at which at least a part of the distal cutting portion faces the cutting window, and a second position at which the distal cutting portion does not face the cutting window, and 
 the control circuitry supplies (i) a first electrical power signal at least part of the time while the second cutting blade is in the first position, and (ii) a second electrical power signal, which is different from the first electrical power signal, at least part of the time while the second cutting blade is in the second position. 
 
     
     
       16. A surgical cutting instrument comprising:
 a first cutting blade having a tubular body with a proximal end and a distal end, a cutting window disposed at a side of the first cutting blade near the distal end; 
 a second cutting blade having a tubular body with a proximal end and a distal end, a cutting window disposed at a side of the second cutting blade near the distal end, the second cutting blade rotatably disposed inside of the first cutting blade such that the surgical cutting instrument cuts tissue by rotating the second cutting blade within the first cutting blade while a vacuum is applied through an internal bore of the second cutting blade to draw the tissue into the cutting windows of the first and second cutting blades and sever the tissue by rotation of the second cutting blade; 
 at least one first electrode located adjacent to at least the cutting window at the distal end of the first cutting blade; 
 a sensor that senses a rotational position of the second cutting blade relative to the first cutting blade; and 
 a processor that controls an electrical power signal supplied to the at least one first electrode at least partially based on the sensed rotational position of the second cutting blade relative to the first cutting blade, the processor supplying (i) a first electrical power signal at least part of the time while the cutting windows of the first and second cutting blades are aligned with each other, and (ii) a second electrical power signal, which is different from the first electrical power signal, at least part of the time while the cutting windows of the first and second cutting blades are not aligned with each other. 
 
     
     
       17. A surgical cutting instrument comprising:
 a first cutting blade having a tubular body with a proximal end and a distal end, a cutting window disposed at a side of the first cutting blade near the distal end; 
 a second cutting blade having a tubular body with a proximal end and a distal end, a cutting window disposed at a side of the second cutting blade near the distal end, the second cutting blade rotatably disposed inside of the first cutting blade such that the surgical cutting instrument cuts tissue by rotating the second cutting blade within the first cutting blade while a vacuum is applied through an internal bore of the second cutting blade to draw the tissue into the cutting windows of the first and second cutting blades and sever the tissue by rotation of the second cutting blade; 
 at least one first electrode located adjacent to at least the cutting window at the distal end of the first cutting blade; and 
 control circuitry coupled to at least the second cutting blade and that supplies an electrical power signal to the at least one first electrode, the control circuitry supplying (i) a first electrical power signal at least part of the time while the cutting windows of the first and second cutting blades are aligned with each other, and (ii) a second electrical power signal, which is different from the first electrical power signal, at least part of the time while the cutting windows of the first and second cutting blades are not aligned with each other.